Scale and Corrosion Inhibitors in Water Treatment Chemicals
Scale inhibitors are one of the important water treatment chemicals. At present, scale inhibitors are mainly used for scale inhibition and sustained release of circulating water. They are widely used for water treatment of boiler water, oil field water, etc.
The scale inhibitor is a kind of medicament which has a poorly soluble inorganic salt capable of dispersing in water, prevents or interferes with precipitation and scaling of a poorly soluble inorganic salt on a metal surface, and maintains a good heat transfer effect of a metal device.
Scale inhibitors not only control scale, but also control corrosion products, slime, and sludge to some extent. A large amount of scale-forming material can be controlled by adding a small amount of scale inhibitor.
Early use of scale inhibitors is processed natural polymer products such as starch, sodium gluconate, tannin, sulfonated lignin and the like. The natural scale inhibitor has the advantages of low price and no pollution, but its scale inhibition rate is low, so the dosage of the medicament is large.
In the 1960s, the company developed new scale inhibitors, which were synthetic or polymeric products, scale inhibitors, and higher scale inhibition rate than natural scale inhibitors, which can meet the requirements of higher scale inhibition.
It is generally believed that its scale inhibition mechanism is as follows.
Inorganic scale (such as calcium carbonate) crystals are arranged in a certain lattice when growing. The crystal is dense and relatively strong. When a polycarboxylic acid or an organophosphate (phosphonic acid or organophosphate) scale inhibitor is contained in water, the group of the scale inhibitor has a chelation ability to the metal ion. It interferes with the crystal of inorganic scale, causing the crystal lattice to be distorted and become an irregular crystal. This is the lattice distortion effect.
Lattice distortion causes a hard scale to become amorphous and soft. The crystal of the scale is not easy to grow, and there are a large number of voids in the scale layer, and the adhesion force to each other is poor, and it is easily washed away in the water flow and can be discharged together with the sewage.
ATMP is added to the circulating water because it has good miscibility, it can prevent the formation of scale in the scale, especially the formation of calcium carbonate scale.
ATMP acid is used in circulating water in thermal power plants and refineries to reduce corrosion and scaling of metal equipment or pipelines.
ATMP chemical is used as a metal ion chelating agent in the textile printing and dyeing industry. Prolonged exposure to air or water in metal equipment can cause some corrosion and scaling, and then the metal surface can be well treated by adding a certain amount of amino trimethylene phosphonic acid.
Scale inhibitors are important water treatment chemicals and one of the largest product categories in water treatments. Therefore, the water treatment chemical cannot bypass the scale inhibitor.